The present invention is directed to the recovery of molybdenum from the bottoms fraction in the epoxidation of olefins, especially the epoxidation of propylene with an organic hydroperoxide.
Powell U.S. Pat. No. 2,778,777 discloses treating crude petroleum containing small amounts of water insoluble molybdenum compounds by treating the petroleum with dilute sulfuric acid to form water soluble metal salts, forming an aqueous phase and separating the purified oil from the aqueous phase. No mention is made of the problem of separation of molybdenum from the bottoms fraction in the epoxidation of an olefin or in separation from a mixture containing alcohols, esters, and ethers.
Kollar U.S. Pat. No. 3,351,635 is the basic patent on the preparation of an epoxide by the reaction of an olefin, e.g. propylene, with an organic hydroperoxide employing a molybdenum catalyst. Thereby there are obtained the epoxide, e.g. propylene oxide, and the alcohol corresponding to the hydroperoxide, e.g. t-butyl alcohol if the hydroperoxide is t-butyl hydroperoxide. However, Kollar makes no mention of the bottoms material or of recovery molybdenum. The entire disclosure of Kollar is hereby incorporated by reference and relied upon.
Tave U.S. Pat. No. 3,463,604 is directed to the recovery of molybdenum from a molybdenum containing organic solution obtained from the bottoms fraction of the reaction product of an organic soluble molybdenum compound catalyzed olefin epoxidation process by contacting the molybdenum containing organic solution with an aqueous ammonium phosphate solution with a mole ratio of ammonium phosphate to molybdenum in the range of 0.8:1 to 2.0:1 and the concentration of water in the range of about 4 to 5 weight percent based on the molybdenum containing organic solution and the ammonium phosphate solution to precipitate ammonium phosphomolybdate. Tave points out that if the bottoms containing organic stream is alkaline it should be made acidic, column 3, lines 54-65. There is no mention made of forming a separate aqueous phase and in fact the contrary is indicate on column 4, lines 36-47. The entire disclosure of Tave is hereby incorporated by reference and relied upon.
Levine U.S. Pat. No. 3,819,663 is directed to a process for the epoxidation of an olefin compound with an organic hydroperoxide in the presence of a molybdenum epoxidation catalyst in which after removal of the product fraction the heavy liquid fraction containing the molybdenum catalyst is subjected to a wiped film evaporation at 375.degree. to 450.degree. F. to remove 60 to 85% by weight of the fraction as overhead, optionally further heating to 550.degree. to 650.degree. F., and recycling the evaporation residue to the epoxidation. This procedure necessary destroys a part of the heavy organics and does not truly separate the molybdenum values, e.g. they will contain carbonaceous material according to Example 5. The entire disclosure of Levine is hereby incorporated by reference and relied upon.
Schmidt U.S. Pat. No. 4,140,588 shows the use of water as an extractive distillation agent in the separation of methanol and acetone from propylene oxide made by the Kollar process. Schmidt also mentions various materials formed in the reaction and other methods tried for purification, e.g. column 1, line 5 to column 2, line 9.